Constructing van der Waals heterostructures by dry-transfer assembly for novel optoelectronic device

Atrazine concentration detection based on NiAl-layer double hydroxides nanosheets synaptic transistor

A transistor inspired by biological systems, which possesses synaptic and sensing capabilities, has demonstrated significant promise in the field of neuromorphic electronics and sensory systems resembling the human brain. Despite the remarkable advancements in emulating neuromorphic operations, the development of a synaptic FET with a bionic architecture, extended lifespan, minimal energy usage, and marker monitoring capability remains challenging. In this work, a synaptic transistor based on NiAl-layer double hydroxides nanosheets is reported. The synaptic transistor exhibits a significant ratio of on/off current (1.35×107) and possesses a high transconductance value (10.05 mS). The successful emulation included key synaptic characteristics, such as excitatory/inhibitory postsynaptic current, paired-pulse facilitation/depression, short-term plasticity spike amplitude-dependent plasticity, spike timing-dependent plasticity, as well as spike number-dependent plasticity. A consumption of 64.8 pJ per spike was achieved as a result of the efficient carrier transfer pathway facilitated by the nanosheets composed of double hydroxides. In addition, the FET's linear detection region (with a coefficient R2=0.811) encompassed atrazine concentrations ranging from 10 pg/mL to 0.1 μg/mL, thanks to its high surface area and significant transconductance. Therefore, this study presents a potential approach for achieving energy-efficient neuromorphic computing and high-performance synaptic devices.

Optoelectronic neuron based on transistor combined with volatile threshold switching memristors for neuromorphic computing

The human perception and learning heavily rely on the visual system, where the retina plays a vital role in preprocessing visual information. Developing neuromorphic vision hardware is based on imitating the neurobiological functions of the retina. In this work, an optoelectronic neuron is developed by combining a gate-modulated PDVT-10 channel with a volatile threshold switching memristor, enabling the achievement of optoelectronic performance through a resistance-matching mechanism. The optoelectronic spiking neuron exhibits the ability to alter its spiking behavior in a manner resembling that of a retina. Incorporating electrical and optical modulation, the artificial neuron accurately replicates neuronal signal transmission in a biologically manner. Moreover, it demonstrates inhibition of neuronal firing during darkness and activation upon exposure to light. Finally, the evaluation of a perceptron spiking neural network utilizing these leaky integrate-and-fire neurons is conducted through simulation to assess its capability in classifying image recognition algorithms. This research offers a hopeful direction for the development of easily expandable and hierarchically structured spiking electronics, broadening the range of potential applications in biomimetic vision within the emerging field of neuromorphic hardware.

Controlled Preparation of High Quality Bubble-Free and Uniform Conducting Interfaces of Vertical van der Waals Heterostructures of Arrays

Sharp and clean interfaces of van der Waals (vdW) heterostructures are highly demanded in two-dimensional (2D) materials-based devices. However, current assembly methods usually cause interfacial bubbles and wrinkles, hindering carrier interlayer transport. The preparation of a large-scale vdW heterostructure with a bubble-free interface is still a challenge. Although many efforts have been made to eliminate bubbles, the evolution processes of the interfacial bubbles are rarely studied. Here, the interface bubble formation and evolution of the transferred 2D materials and their vdW heterostructure are systemically studied by the atomic force microscopy (AFM) technique and high-resolution surface current mapping. A thermal annealing procedure is developed to reduce the number of bubbles and to improve the quality of interfaces. In addition, influences of the interface residues and nanosteps on bubble evolution are also discussed. Further, we develop the polystyrene (PS)-mediated polydimethylsiloxane (PDMS) transfer technique to realize the high-quality transfer of heterostructure arrays. Finally, high-resolution surface current mapping results confirm that we can now produce highly uniform electrical conduction interfaces of heterojunctions. This study provides guidance for assembling high quality interfaces and paves the way for production of bubble-free heterostructure-based electronic devices with high performance and good uniformity.